Implantable medical devices such as the left ventricular assist device, the totally artificial heart, certain hearing assist devices and neurostimulators, because of their high level of power consumption, require rechargeable batteries. Conventional Ni/Cd and Pb-acid batteries do not possess the energy density to provide adequate operating capacity for these devices. A rechargeable Li-ion battery utilizing a polymer electrolyte is potentially capable of very high specific energy (>200 Wh/kg), long cycle life, exceptional safety due to the absence of volatile liquids, and design flexibility for implantable applications. We propose to develop such a battery based on a novel solvent-free polymer electrolyte with conductivity similar to liquid electrolytes at room temperature. In Phase I, we will prepare and characterize the new polymer electrolytes, composed of hybrids of Li+-conductive inorganic materials and new highly ion- conductive organic polymer electrolytes. The suitability of the new solid polymer electrolytes will be assessed in Li-ion batteries. PROPOSED COMMERCIAL APPLICATIONS: The polymer electrolyte to be developed in this program can become the basis for primary Li batteries for heart pacemakers, and rechargeable Li- ion batteries for ventricular assist devices, totally artificial heart and implantable cochlear and neuro-stimulators. Other non-medical applications for polymer batteries are in cellular phones, lap-top computers, pagers and hand-held tools.